A teaching-learning module, aimed at introducing basic concepts of general relativity at the high school level, is proposed. Emphasis is on conceptual rather than technical aspects, and only familiarity with simple calculus is required on the mathematical side. The starting point is a critical overview of the principles of Newtonian mechanics, in particular the role of fictitious forces, as well as of the limits of special relativity. Part of the module is devoted to the discussion and the reproduction of key thought or real experiments, for example experiments involving non-inertial frames, or the Einstein elevator.